1. Field of the Invention
This invention relates to a lens-fited film unit with a data recording device incorporated therein in which the utilization is made of external light to form a data image on a film.
2. Description of Related Art
Easy-use lens-fitted film units are well known. Such a lens-fitted film unit has a film unit housing comprising a main housing section with a film cartridge loaded therein and front and back cover sections attached to the main housing section. The main housing section is provided with various mechanisms or units, such as a shutter mechanism, a taking lens, an exposure unit and a flash unit. When a film is fully exposed, the lens-fitted film unit is forwarded to a photo-laboratory where the film cartridge with the exposed film rewound therein is taken out of the film unit housing and processed for development and printing. The developed film and prints are returned as one set to the customer.
Some types of the lens-fitted film units are provided with a data recording device for recording a calendar date on the film. Such a lens-fitted film unit is known from, for instance, Japanese Unexamined Patent Publication No. 5-289164. According to the Japanese publication mentioned above, the data recording device built in the lens-fitted film unit has a manual data setting dial by means of which a calendar date is set and a data recording optical system comprising an optical light guide through which external light is introduced to illuminate a data display plate and bear an image of the data to the back of the film. In this data recording device, the utilization is made of external light passing through the taking lens and then traveling to the data display plate disposed behind the film through the optical light guide which extends under an exposure chamber between the taking lens and an exposure aperture frame.
In the lens-fitted film unit with the data recording device described above, because the data display plate and the manual data setting dial are installed to the back cover, the film unit housing unavoidably juts backward and has a large thickness, which are undesirable for handiness of the lens-fitted film unit. In cases where the lens-fitted film unit has a built-in flash unit, the film unit housing is increased in height due to a flash battery which is placed under the exposure chamber together with the optical light guide. Further, in cases where the lens-fitted film unit has a contact exposure type of data recording device, the data display plate is placed slightly apart from the film in order to prevent the film from scratch marks. For this reason, the data is blurred on a print and unclear on, in particular, an enlarged print. The photographer of this type of lens-fitted film unit encounters somewhat troublesome data setting operation.
In order for the lens-fitted film unit to have a thin film unit housing, it is preferable to project a data onto the film from the front. For this purpose, a data exposure aperture is provided near a subject exposure aperture to introduce external light toward the film, which is opened and closed by a data exposure shutter cooperating with a subject exposure shutter for opening and closing the subject exposure aperture. This makes it possible to expose the film to a subject image and a data image simultaneously. However, the lens-fitted film unit of the type of projecting a data onto the film from the front has a need to incorporate a data display member between the exposure unit and the front cover section, encounters a difficulty with a thin film unit housing,
While a data may be projected onto the film from the front by means of the data exposure aperture and shutter to form a latent image of the data together with a subject image in response to operation of a shutter release member as described above, if the data exposure shutter is provided integrally with the subject exposure shutter, it is necessary to prevent the data exposure shutter from partly crossing the subject exposure aperture in the course of opening the subject exposure aperture. This is because, if the data exposure shutter partly crossing the subject exposure aperture, the subject image encounters a lack of evenness in exposure. Regarding the lens-fitted film unit described in the Japanese publication mentioned above, exposure of the film to a data image is made by external light introduced through the data exposure aperture opened by the data exposure shutter while the subject exposure shutter opens the subject exposure aperture, it experiences a lack of light. Accordingly, there is a strong demand for making the utilization of a lens to make up the insufficient amount of light. This has a need to adjust the lens in axial position and hold it so as to prevent a positional shift due to vibrations. In addition, in view of automatic assembly of the lens-fitted film unit, easiness and convenience of assembling the lens-fitted film unit must be taken into consideration.
Conventional lens-fitted film units, in particular, having data recording devices have less adaptability for recycling. That is, while the data recording device described above is protected from damages by the front and back covers, and hence it is recycled without repair, nevertheless, the data display plate and the manual data setting dial must be detached from the back cover which is one of recycling parts. During detaching work, these parts possibly encounters damages.